[PATCH] D24410: Use call target count to derive the call instruction weight

[Dehao Chen via llvm-commits]

danielcdh created this revision.
danielcdh added reviewers: dnovillo, davidxl.
danielcdh added a subscriber: llvm-commits.

The call target count profile is directly derived from LBR branch->target data. This is more reliable than instruction frequency profiles that could be moved across basic block boundaries. This patches uses call target count profile to annotate call instructions.

https://reviews.llvm.org/D24410

Files:
  include/llvm/ProfileData/SampleProf.h
  lib/Transforms/IPO/SampleProfile.cpp
  test/Transforms/SampleProfile/Inputs/inline-coverage.prof

Index: test/Transforms/SampleProfile/Inputs/inline-coverage.prof
===================================================================
--- test/Transforms/SampleProfile/Inputs/inline-coverage.prof
+++ test/Transforms/SampleProfile/Inputs/inline-coverage.prof
@@ -4,4 +4,4 @@
  4: 0
  0: 0
  3: _Z3fool:172746
-  1: 31878
+  1: 31878 rand:31878
Index: lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- lib/Transforms/IPO/SampleProfile.cpp
+++ lib/Transforms/IPO/SampleProfile.cpp
@@ -479,7 +479,8 @@
 
   uint32_t LineOffset = getOffset(Lineno, HeaderLineno);
   uint32_t Discriminator = DIL->getDiscriminator();
-  ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
+  ErrorOr<uint64_t> R = CI ? FS->findCallSamplesAt(LineOffset, Discriminator):
+                             FS->findSamplesAt(LineOffset, Discriminator);
   if (R) {
     bool FirstMark =
         CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
Index: include/llvm/ProfileData/SampleProf.h
===================================================================
--- include/llvm/ProfileData/SampleProf.h
+++ include/llvm/ProfileData/SampleProf.h
@@ -222,6 +222,21 @@
       return ret->second.getSamples();
   }
 
+  /// Return the total number of call target samples collected at a given
+  /// location. Each location is specified by \p LineOffset and
+  /// \p Discriminator. If the location is not found in profile, return error.
+  ErrorOr<uint64_t> findCallSamplesAt(uint32_t LineOffset,
+                                      uint32_t Discriminator) const {
+    const auto &ret = BodySamples.find(LineLocation(LineOffset, Discriminator));
+    if (ret == BodySamples.end())
+      return std::error_code();
+    uint64_t T = 0;
+    for (const auto &t_c : ret->second.getCallTargets()) {
+      T += t_c.second;
+    }
+    return T;
+  }
+
   /// Return the function samples at the given callsite location.
   FunctionSamples &functionSamplesAt(const LineLocation &Loc) {
     return CallsiteSamples[Loc];


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